Sensor

ABSTRACT

A sensor which uses a detection element such as a surface acoustic wave element, and includes a flow passage for a specimen is provided. A sensor includes a substrate; a detection element located on the substrate and having a detection portion which detects an object to be detected contained in a specimen, in an upper surface thereof; and a flow passage structure located on the substrate and covering the detection portion with a space. The flow passage structure has an inlet for the specimen, a flow passage continuing from the inlet, and a space which continues from an end portion of the flow passage closer to the detection element and is located above the detection portion, and a bottom surface of the flow passage has, on the end portion of the flow passage closer to the detection element, a notched portion whose width gradually decreases toward an upstream of the flow passage.

RELATED APPLICATIONS

This application is a 35 U.S.C. §371 U.S. National Phase Application of PCT/JP2013/076533, which was filed on Sep. 30, 2013, which claims priority to Japanese Patent Application No. 2013-016924 filed on Jan. 31, 2013 and Japanese Application No. 2013-068618 filed on Mar. 28, 2013. The disclosures of these applications are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a sensor capable of measuring a property of a specimen or an ingredient contained in a specimen.

BACKGROUND ART

There has been known a sensor that is used in measuring a property of a liquid containing an object to be detected or an ingredient of a liquid containing an object to be detected, using a detection element such as a surface acoustic wave element.

Patent Literature 1 discloses a technology of a sensor capable of introducing a liquid containing an object to be detected to a detection portion by utilizing capillary phenomenon. This technology is such that a long and thin specimen supply flow passage is directed to a part where a reagent of a measurement electrode is applied and the specimen is introduced to the part where the reagent is applied, by capillary phenomenon.

CITATION LIST

Patent Literature 1: Japanese Unexamined Patent Publication JP-A 2005-249491

SUMMARY OF INVENTION Technical Problem

In passing a liquid containing an object to be detected through a flow passage by utilizing capillary phenomenon as in the technology described in Patent Document 1 may occur a problem that the object to be detected stops in the middle of the flow passage before the object to be detected reaches a detection portion and the object to be detected does not reach the detection portion.

Accordingly, it is desired to provide a sensor capable of inhibiting a liquid containing an object to be detected from stopping in the middle of the flow passage in passing the liquid through the flow passage by utilizing capillary phenomenon.

Solution to Problem

A sensor according to an embodiment of the invention includes a substrate; a detection element located on the substrate and having a detection portion which detects an object to be detected contained in a specimen on an upper surface thereof; and a flow passage structure located on the substrate and covering the detection portion with a space, the flow passage structure having an inlet for the specimen, a flow passage continuing from the inlet, and a space which continues from an end portion of the flow passage closer to the detection element and is located above the detection portion, a bottom surface of the channel having, on the end portion of the flow passage closer to the detection element, a notched portion whose width gradually decreases toward an upstream of the flow passage.

Advantageous Effects of Invention

According to the sensor of the above-described embodiment, since the notched portion whose width gradually decreases toward the upstream of the flow passage is provided at the exit portion of the bottom surface of the flow passage closer to the detection element, the specimen is allowed to smoothly flow to the detection portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a sensor according to a first embodiment of the invention;

FIG. 2 is an exploded perspective view of the sensor shown in FIG. 1;

FIG. 3 is a plan view of a detection element used in the sensor shown in FIG. 1;

FIG. 4 is a perspective view of a flow passage structure used in the sensor shown in FIG. 1;

FIG. 5 is a cross-sectional view of the sensor shown in FIG. 1 taken along the line A-A′;

FIG. 6 is a plan view of the sensor shown in FIG. 1 under a condition where a second hydrophilic sheet is removed;

FIG. 7 is a cross-sectional view of a sensor of a comparative example;

FIG. 8 is a plan view in which a notched portion of the sensor shown in FIG. 1 is enlarged;

FIGS. 9( a)-9(b) illustrate enlarged plan views showing various examples of the planar shape of the notched portion;

FIG. 10 is a cross-sectional view of a sensor according to a second embodiment of the invention;

FIG. 11 is an enlarged plan view of a notched portion of the sensor shown in FIG. 10;

FIG. 12 is an enlarged cross-sectional view of a notched portion of the sensor shown in FIG. 10;

FIG. 13 is a cross-sectional view showing a modified example of the sensor according to the first embodiment;

FIG. 14 is a cross-sectional view showing a modified example of the sensor according to the first embodiment;

FIG. 15 is a cross-sectional view of a sensor according to a third embodiment of the invention;

FIG. 16 is a cross-sectional view of a measurement sample of the second embodiment;

FIGS. 17( a)-17(b) illustrate cross-sectional views showing modified examples of the sensor according to the first embodiment;

FIG. 18 is a plan view of the sensor shown in FIG. 17( a) under a condition where a second hydrophilic sheet is removed; and

FIGS. 19( a)-19(b) illustrate cross-sectional views showing modified examples of the sensor according to the first embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of a sensor according to the invention will be described in detail with reference to the drawings. In the drawings described below, the same component members are denoted by the same reference numerals. Moreover, the sizes of the members, the distances between the members and the like are schematically illustrated and sometimes different from the actual ones.

Moreover, while any direction may be regarded as the upward direction or the downward direction in sensors, in the following, for convenience's sake, orthogonal coordinate systems xyz are defined and with the positive side in the z direction as the upward direction, terms such as an upper surface and a lower surface are used.

First Embodiment

FIG. 1 shows a perspective view of a sensor 100. The sensor 100 mainly comprises a substrate 1, a flow passage structure 2 and a detection element 3.

The flow passage structure 2 is disposed on the substrate 1 through the detection element 3 and a support member 4 as shown in FIG. 1. The flow passage structure 2 has an inlet 14 which is an entrance for a liquid-form specimen (hereinafter, sometimes referred to as specimen liquid) on the side of one end portion in the direction of the length (x direction), and as shown in FIG. 5, a flow passage 29 connecting with the inlet 14 is formed inside.

FIG. 2 shows an exploded perspective view of the sensor 100.

The substrate 1 is planar, and the thickness thereof is, for example, 0.1 mm to 0.5 mm. The length of the substrate 1 in the x direction is, for example, 1 cm to 5 cm, and the length in a y direction is, for example, 1 cm to 3 cm. The substrate 1 is, for example, a resin substrate or a ceramic substrate, and wiring or the like may be laid on the surface or inside.

On one end portion of an upper surface of the substrate 1, the detection element 3 is mounted. Moreover, on both sides of the one end portion of the upper surface of the substrate 1, a plurality of terminals 6 are provided. The plurality of terminals 6 are electrically connected to the detection element 3. When attached to a reading device outside the sensor 100, terminals of the reading device make contact with the terminals 6. Thereby, an electric signal from the sensor 100 is outputted to the external reading device through the terminals 6. A structure including such a sensor 100 and an external reading device can constitute a sensor device.

FIG. 3 shows a plan view of the detection element 3.

In the sensor 100, the detection element 3 is a surface acoustic wave element, and mainly comprises a piezoelectric substrate 10, a first IDT (InterDigital Transducer) electrode 11, a second IDT electrode 12 and a detection portion 13.

The piezoelectric substrate 10 is formed of, for example, a substrate of a single crystal having piezoelectricity such as a lithium tantalate (LiTaO₃) single crystal, a lithium niobate (LiNbO₃) single crystal or crystal. The planar shape and various dimensions of the piezoelectric substrate 10 may be set as appropriate. As an example, the thickness of the piezoelectric substrate 10 is 0.3 mm to 1.0 mm.

The first IDT electrode 11 has a pair of comb-like electrodes. Each comb-like electrode has two bus bars facing each other and a plurality of electrode fingers extending from each bus bar toward another bus bar. In the pair of comb-like electrodes, a plurality of electrode fingers are disposed so as to engage with each other. The second IDT electrode 12 is structured similarly to the first IDT electrode 11. The first IDT electrode 11 and the second IDT electrode 12 constitute a transversal IDT electrode.

The first IDT electrode 11 is configured to generate a predetermined surface acoustic wave (SAW), and the second IDT electrode 12 is for receiving the SAW generated at the first IDT electrode 11. The first IDT electrode 11 and the second IDT electrode are collinearly disposed so that the second IDT electrode 12 can receive the SAW generated at the first IDT electrode 11. The frequency characteristic may be designed with the following and the like as parameters: the number of electrode fingers of the first IDT electrode 11 and the second IDT electrode 12, the distances between the adjoining electrode fingers and the crossing widths of the electrode fingers. As the SAW excited by the IDT electrode, waves of various oscillation modes are present, and in the detection element 3, for example, an oscillation mode of a lateral wave called SH wave is used.

Moreover, on the outside of the first IDT electrode 11 and the second IDT electrode 12 in the SAW propagation direction (y direction), an elastic member for SAW reflection suppression may be provided. The frequency of the SAW may be set, for example, within a range of several megahertz (MHz) to several gigahertz (GHz). Above all, setting it at several MHz to 2 GHz is practical, and enables the realization of downsizing of the detection element 3, further, downsizing of the sensor 100.

The first IDT electrode 11 is connected to a first extraction electrode 19. The first extraction electrode 19 is extracted from the first IDT electrode 11 to a side opposite to the detection portion 13, and an end portion 19 e of the first extraction electrode 19 is electrically connected through a thin metal wire to a pad 7 provided on the substrate 1. Moreover, the second IDT electrode 12 is connected to a second extraction electrode 20. The second extraction electrode 20 is extracted from the second IDT electrode 12 to a side opposite to the detection portion 13, and an end portion 20 e of the second extraction electrode 20 is electrically connected through a metal wire to the pad 7.

The first IDT electrode 11, the second IDT electrode 12, the first extraction electrode 19 and the second extraction electrode 20 are formed of, for example, aluminum or an alloy of aluminum and copper. Moreover, these electrodes may have a multi-layer structure. In the case of a multi-layer structure, for example, the first layer is formed of titanium or chromium, and the second layer is formed of aluminum or an aluminum alloy.

The first IDT electrode 11 and the second IDT electrode 12 are covered with a protective film (not shown). The protective film contributes to prevention of oxidation of the first IDT electrode 11 and the second IDT electrode 12, and the like. The protective film is formed of, for example, silicon oxide, aluminum oxide, zinc oxide, titanium oxide, silicon nitride or silicon (silicon). The thickness of the protective film is, for example, approximately 1/10 of the thickness of the first IDT electrode 11 and the second IDT electrode (10 to 30 nm). The protective film is formed over the entire area of an upper surface of the piezoelectric substrate 10 so that the end portion 19 e of the first extraction electrode 19 and the end portion 20 e of the second extraction electrode 20 are exposed.

The detection portion 13 is provided between the first IDT electrode 11 and the second IDT electrode 12. The detection portion 13 is formed on the protective film. The detection portion 13 is formed of, for example, a metal film and an aptamer immobilized on the surface of the metal film. The metal film has a two-layer structure of, for example, chromium and gold formed on the chromium. The aptamer is formed of, for example, nucleic acid or peptide. The detection portion 13 is for causing a reaction with the target substance in the specimen liquid; specifically, when the specimen liquid makes contact with the detection portion 13, a specific target substance in the specimen liquid binds to the aptamer corresponding to the target material.

When the first IDT electrode, the second IDT electrode and the detection portion 13 disposed in the y direction are regarded as one set, two sets are provided in the sensor 100. With this, by making the target substance reacting at one detection portion 13 different from the target substance reacting at the other detection portion 13, two kinds of detections can be performed with one sensor.

On the first and second IDT electrodes 11 and 12, a first adhesion layer 21 described later is disposed. Thereby, the first and second IDT electrodes 11 and 12 are covered with the first adhesion layer 21, and therefore the first and second IDT electrodes 11 and 12 are separated from the outside air and the specimen liquid, so that the first and second IDT electrodes 11 and 12 can be protected.

To detect a specimen liquid in the detection element 3 using the SAW as described above, first, a predetermined voltage is applied to the first IDT electrode 11 from an external reading device. Then, the surface of the piezoelectric substrate 10 is excited in an area where the first IDT electrode 11 is formed, so that a SAW having a predetermined frequency is generated. The generated SAW partly propagates toward the detection portion 13 and passes the detection portion 13 to reach the second IDT electrode 12. At the detection portion 13, the aptamer of the detection portion 13 binds to a specific target substance in the specimen liquid and the binding changes the weight of the detection portion 13, so that a characteristic such as the phase of the SAW passing below the detection portion 13 changes. When the SAW whose characteristic has thus changed reaches the second IDT electrode, a voltage according thereto occurs at the second IDT electrode. This voltage is outputted to the outside through the second extraction electrode 20 or the like and read by an external reading device, whereby properties and ingredients of the specimen liquid can be examined.

The detection element 3 is fixed to the upper surface of the substrate 1 by a die bond material containing, for example, epoxy resin, polyimide resin or silicone resin as a main component. As shown in FIG. 2, the end portion 19 e of the first extraction electrode 19 and the pad 7 are electrically connected by a thin metal wire 5 formed of, for example, Au. The connection between the end portion 20 e of the second extraction electrode 20 and the pad 7 is similar. Although not shown in FIG. 1 and FIG. 2, the thin metal wire 5 is covered with an insulating member formed of a resin or the like. Thereby, corrosion of the thin metal wire 5 can be suppressed.

Moreover, in the sensor 100 of the present embodiment, on the upper surface of the substrate 1, the support member 4 is mounted in addition to the detection element 3. The support member 4 is a member for supporting the flow passage structure 2. On an upper surface of the support member 4, the flow passage structure 2 is mounted. The thickness of the support member 4 is substantially the same as the size of a space formed between the substrate 1 and the flow passage structure 2. The thickness is, for example, 0.2 mm to 1 mm. The length of the support member 4 in the x direction is shorter than the length of the substrate 1 in the x direction, and the length is, for example, 0.6 cm to 3 cm. The length of the support member 4 in the y direction is the same as, for example, the length of the substrate 1 in the y direction.

The support member 4 is formed of paper, plastic, celluloid or ceramics. The support member 4 is fixed to the substrate 1 by an adhesive agent or the like.

The flow passage structure 2 is bonded to the detection element 3, and the support of the flow passage structure 2 the support member 4 makes it possible to suppress the occurrence of separation at the bonding part of the flow passage structure 2 and the detection element 3.

The flow passage structure 2 is disposed on the substrate 1 so as to cover at least part of the detection element 3. The flow passage structure 2 is formed of, as shown in FIG. 2, the first adhesion layer 21, a first hydrophilic sheet 22, a second adhesion layer 23 and a second hydrophilic sheet 24, and these are laminated in order.

The first adhesion layer 21 is formed of a material containing, for example, polyethylene as a main component, and has an adherence property on both surfaces thereof. The first adhesion layer 21 is a frame member having a through hole 21 h in the center thereof. The length of the first adhesion layer 21 in the x direction is substantially the same as or somewhat larger than the length of the detection element 3 in the x direction, and the length in the y direction is slightly shorter than the length of the detection element 3 in the y direction and is such a width that end portions of the first and second extraction electrodes 19 and 20 can be seen. The thickness of the flow passage structure 21 is, for example, 0.1 mm to 0.5 mm.

The through hole 21 h has the shape of a rectangle having a triangular cutout at one end portion thereof, and is a pentagon in the shape of a home base as a whole. The width of the rectangular part of the through hole 21 h in the y direction is substantially the same as the width of the detection portion 13 in the y direction.

The first adhesion layer 21 is disposed on an upper surface of the detection element 3. Since the first adhesion layer 21 has an adherence property, the flow passage structure 2 is bonded to the detection element 3 by this first adhesion layer 21.

The dotted line shown in FIG. 3 indicates the position of the through hole 21 h under a condition where the first adhesion layer 21 is disposed on the upper surface of the detection element 3. As shown in the figure, two detection portions 13 are exposed from the through hole 21 h under the condition where the first adhesion layer 21 is disposed on the upper surface of the detection element 3. On the other hand, the first and second IDT electrodes 11 and 12 are located below the frame of the first adhesion layer 21. By disposing the first and second IDT electrodes 11 and 12 below the frame of the first adhesion layer 21, contact of the first and second IDT electrodes 11 and 12 with the specimen liquid can be suppressed.

When the first and second IDT electrodes 11 and 12 are located below the frame of the first adhesion layer 21 like this, it is preferable that the first adhesion layer 21 is formed of a material having a lower modulus of elasticity than the protective film covering the first and second IDT electrodes 11 and 12. By forming the first adhesion layer 21 of a material having a lower modulus of elasticity than the protective film, the propagation loss of the SAW can be made smaller than otherwise. For example, when silicon oxide such as SiO₂ is used as the protective film, silicone resin having a lower modulus of elasticity than silicon oxide may be used as the first adhesion layer 21.

To further reduce the propagation loss of the SAW, the width of the through hole 21 h is increased so that the first and second IDT electrodes 11 and 12 can be seen through the through hole 21 h. In this case, since a condition is brought about where nothing other than the protective layer is placed in the area above the first and second IDT electrodes 11 and 12 and the propagation path of the SAW between the first IDT electrode 11 and the second IDT electrode 12, the propagation loss of the SAW can be further reduced.

Returning to FIG. 2, the first hydrophilic sheet 22 is laminated on the first adhesion layer 21. Part of an upper surface of the first hydrophilic sheet 22 is a part that becomes a bottom surface 29 b of the flow passage 29. Specifically, of the upper surface of the first hydrophilic sheet, the part exposed from a through hole 23 h of the second adhesion layer 23 laminated on the first hydrophilic sheet 22 becomes the bottom surface 29 b of the flow passage 29.

The planar shape of the first hydrophilic sheet 22 is, for example, a rectangle. The length of the first hydrophilic sheet 22 in the x direction is, for example, substantially the same as the length of the substrate 1 in the x direction, and the length in the y direction is, for example, approximately half the length of the substrate 1 in the y direction. The thickness of the first hydrophilic sheet 22 is, for example, 0.1 mm to 0.5 mm.

Moreover, on the side of one end portion of the first hydrophilic sheet 22, a through hole 22 h is provided. The through hole 22 h has the same shape and the same size as the through hole 21 h provided on the first adhesion layer 21, and when the first hydrophilic sheet 22 is laminated on the first adhesion layer 21, the through hole 22 h and the through hole 21 h just coincide with each other.

Of the upper surface of the first hydrophilic sheet 22, at least the part that becomes the bottom surface 29 b of the flow passage 29 is hydrophilic. In the sensor 100, the entire area of the upper surface of the first hydrophilic sheet 22 is hydrophilic. By providing a hydrophilic property to the part becoming an inner surface of the flow passage 29 as described above, capillary phenomenon becomes easy to occur. The angle of contact of the upper surface of the first hydrophilic sheet 22 with water is, for example, not more than 70°. A more desirable range of the contact angle is not more than 30°.

To make the upper surface of the first hydrophilic sheet 22 hydrophilic, for example, a hydrophilization treatment is performed on an upper surface of a sheet serving as the first hydrophilic sheet 22. To perform the hydrophilization treatment on the upper surface of the first hydrophilic sheet 22, for example, after ashing is performed by oxygen plasma on an upper surface of a sheet not having undergone the hydrophilization treatment, a saline coupling agent is applied, and polyethyleneglycol is applied lastly. Additionally, a method is also available in which the upper surface of the first hydrophilic sheet 22 is surface-treated by using a treatment agent having phosphorylcholine. Examples of the material for the sheet used as the first hydrophilic sheet 22 include resin, paper, ceramics and glass.

Moreover, a commercially available polyester film, polyethylene film or the like having undergone the hydrophilic treatment may be used.

On the first hydrophilic sheet 22, the second adhesion layer 23 is laminated. The planar shape of the second adhesion layer 23 has, for example, the same shape and the same planar dimensions (dimensions in the x direction and in the y direction) as that of the first hydrophilic sheet 22, and these just coincide with each other under a condition where the second adhesion layer 23 is laminated on the first hydrophilic sheet 22. The thickness of the second adhesion layer 23 is, for example, 0.1 mm to 0.5 mm.

The second adhesion layer 23 has an adherence property on both surfaces thereof, and the second hydrophilic sheet 24 is bonded to the first hydrophilic sheet 22 through the second adhesion layer 23. The second adhesion layer 23 is formed of the same material as the first adhesion layer 21.

In the neighborhood of the center of the second adhesion layer 23 in the y direction, the through hole 23 h extending in the x direction is provided. The second adhesion layer 23 is sandwiched between the first hydrophilic sheet 22 and the second hydrophilic sheet 24 so that the upper and lower openings of the through hole 23 h are closed, whereby the flow passage 29 is formed. That is, the upper surface of the first hydrophilic sheet 22 exposed from the through hole 23 h becomes the bottom surface 29 b of the flow passage 29, and the lower surface of the second hydrophilic sheet 24 exposed from the through hole 23 h becomes the bottom surface 29 b of the flow passage 29. Moreover, an inner peripheral surface of the through hole 23 h becomes a side surface 29 c of the flow passage 29. One end portion of the through hole 23 h extends to the position coinciding with the through hole 22 h of the first hydrophilic sheet 22. The width of the through hole 23 h (dimension in the y direction) is smaller than the width of the through hole 22 h of the first hydrophilic sheet 22. The width of the through hole 23 h is, for example, 0.5 mm to 3 mm.

On the second adhesion layer 23, the second hydrophilic sheet 24 is laminated. The second hydrophilic sheet 24 has the same shape and the same planar dimensions as the second adhesion layer 23, and these just coincide with each other under a condition where the second hydrophilic sheet 24 is laminated on the second adhesion layer 23.

Moreover, in the neighborhood of both end portions of the second hydrophilic sheet 24, the inlet 14 and an outlet 18 each formed of a through hole are provided. The outlet 18 is located on the downstream side of the detection portion 13 of the detection element 3 as shown in FIG. 5. The inlet 14 and the outlet 18 are formed in positions coinciding with the through hole 23 h of the second adhesion layer 23. The inlet 14 is an entrance for pouring the specimen liquid into the flow passage 29. The outlet 18 is a hole for discharging air and the like existing in the flow passage 29 to the outside when the specimen liquid enters the flow passage 29.

Of the lower surface of the second hydrophilic sheet 24, at least the part becoming an upper surface 29 a of the flow passage 29 is hydrophilic. In the sensor 100, the entire area of the lower surface of the second hydrophilic sheet 24 is hydrophilic. The angle of contact of the lower surface of the second hydrophilic sheet 24 with water is, for example, not more than 70°. A more desirable range of the contact angle is not more than 30°.

FIG. 4 is a perspective view when the flow passage structure 2 is viewed from a lower surface side. In FIG. 4, the position of the flow passage 29 is indicated by the dotted line. As shown in FIG. 4, the flow passage structure 2 has a concave portion 9 on the lower surface side. This concave portion 9 is an area surrounded by an inner peripheral surface of the through hole 21 h of the first adhesion layer 21 and the through hole 22 h of the first hydrophilic sheet 22 coinciding with each other and the lower surface of the second adhesion layer 23 and the lower surface of the second hydrophilic sheet 24 exposed from the through hole 22 h.

Such a flow passage structure 2 is disposed on the substrate 1 so that the opening of the concave portion 9 is located on the detection portion 13. At this time, the first adhesion layer 21 is bonded to the upper surface of the detection element 3. Thereby, the detection portion 13 is accommodated in a space 15 surrounded by the upper surface of the detection element 3 and an inner surface of the concave portion 9. As described above, the space 15 is located above the detection portion 13 of the detection element 3, and the flow passage 29 and the space 15 are connected to each other.

Next, the flow of the specimen liquid in the sensor 100 will be described by using FIG. 5. FIG. 5 is a cross-sectional view of the sensor 100 taken along the line A-A′ of FIG. 1, and shows a condition where the specimen liquid 30 has been passed halfway through the flow passage 29.

When the specimen liquid containing the object to be detected makes contact with the inlet 14 provided on the upper surface of the flow passage structure 2, the specimen liquid enters the flow passage 29 by capillary phenomenon.

The angle of contact of the bottom surface 29 b and upper surface 29 a of the flow passage 29 with water is not more than 70°, and when the angle of contact is smaller than 90°, an interface 30 i of the specimen liquid passing through the flow passage 29 takes a parabolic shape (curved shape) concave toward the upstream (−x direction). In other words, the interface 30 i of the specimen liquid 30 has a parabolic shape (curved shape) concave in a direction opposite to the movement direction. When the interface 30 i of the specimen liquid 30 takes such a shape, surface tension acts in the movement direction of the specimen liquid 30 (−x direction), so that the specimen liquid 30 flows toward the downstream. When the angle of contact of the bottom surface 29 b and the upper surface 29 a with water is smaller than 90°, surface tension similarly acts in the movement direction of the specimen liquid and the specimen liquid 30 flows toward the downstream; however, in order that the specimen liquid 30 flows more reliably, it is preferable that the angle of contact is not more than 30°.

In the sensor 100, as shown in FIG. 5, the bottom surface 29 b of the flow passage 29 is located higher than an upper surface 3 b of the detection element 3. Therefore, a step is formed between the exit to the flow passage 29 of the concave portion 9 and the upper surface 3 b of the detection element 3.

And, in the sensor 100, a predetermined notched portion 8 is formed at a part of exit to the concave portion 9 of the bottom surface 29 b of the flow passage 29 (the end portion of the flow passage 29 closer to the detection element 3). FIG. 6 shows a plan view of the sensor 100 under a condition where the second hydrophilic sheet 24 of the flow passage structure 2 is detached. The upper surface of the first hydrophilic sheet 22 exposed from the through hole 23 h of the second adhesion layer 23 is the bottom surface 29 b of the flow passage 29. As shown in the figure, the notched portion 8 is formed so that the width thereof gradually decreases toward the upstream of the flow passage 29 (the left side of the plane of the figure). Here, the width of the notched portion is the length in a direction orthogonal to a direction of flow in the flow passage 29 (the direction connecting the upstream side and the downstream side), that is, the dimension in the y direction (hereinafter, the same applies unless otherwise specified). The planar shape of the notched portion 8 in the sensor 100 is an isosceles triangle. By providing such a notched portion 8, the specimen liquid can be inhibited from stopping in the middle before reaching the detection portion 13. This phenomenon will be described by using FIG. 7 and FIG. 8.

FIG. 7 is a cross-sectional view of a sensor 101 of a comparative example in which no notched portion 8 is formed, and corresponds to the cross-sectional part of FIG. 5. FIG. 7 shows a condition where the specimen liquid 30 is passed through the flow passage 29. The sensor 101 of the comparative example has the same structure as the sensor 100 except that the notched portion 8 is not provided. That is, in the sensor 101 of the comparative example, the edge of the exit to the concave portion 9 of the flow passage 29 is linear.

The present inventors passed the specimen liquid 30 through the flow passage 29 by using the sensor 101 of the comparative example, and in the sensor 101 of the comparative example, a phenomenon occurred in that the specimen liquid stopped in the neighborhood of the exit to the concave portion 9 of the flow passage 29 and did not flow any further. Cause of the occurrence of such a phenomenon was examined by a simulation. As a result of the simulation, it was found that the phenomenon in that the specimen liquid 30 stops occurs when the angle α of contact of the specimen liquid 30 with the upper surface 29 a of the flow passage 29 and the angle β of contact of the specimen liquid 30 with a wall surface 29 b 1 of the first hydrophilic sheet 22 satisfy the following relationship:

(α+β)>90°  (1).

It is considered that this is because when the contact angle α and the contact angle β satisfy the expression (1), the interface of the specimen liquid 30 bulges toward the side of the movement direction (downstream side) as shown in FIG. 7 and surface tension acts toward a side opposite to a movement direction (upstream side) as shown by a hollow arrow.

Conversely, it is considered that when the contact angle α and the contact angle β satisfy the following relationship:

(α+β)<90°  (2),

the interface of the specimen liquid 30 becomes concave toward the upstream and surface tension acts in the movement direction so that the specimen liquid 30 flows without stopping. For this, the contact angle α and the contact angle β are minimized. In this regard, the contact angle α can be easily reduced by performing a hydrophilization treatment or the like on a ceiling surface (the lower surface of the second hydrophilic sheet 24) 29 a of the flow passage. However, the contact angle β tends to be large for a reason that the hydrophilization treatment is difficult to perform on the wall surface of the first hydrophilic sheet 22. Moreover, performing a hydrophilic treatment on such a part leads to a reduction in sensor production efficiency, increase in cost and the like.

On the other hand, when the notched portion 8 as in the sensor 100 is provided on the flow passage 29, even if the contact angle β is comparatively large, the specimen liquid 30 can be inhibited from stopping at the step portion.

FIG. 8 is a view showing the notched portion 8 in FIG. 6 in enlarged state, and shows a condition where the specimen liquid 30 has been led up to the exit to the concave portion 9 of the flow passage 29. When the notched portion 8 is provided, as the specimen liquid 30 projects toward the concave portion 9 in the sensor 101 of the comparative example, in the sensor 100, the specimen liquid 30 also projects toward the concave portion 9 and the interface 30 i of the specimen liquid 30 is located slightly on the movement direction side of the wall surface 29 b 1 of the notched portion 8. Here, since the notched portion 8 is triangular, the specimen liquid 30 projecting from a side of one side of the triangle and the specimen liquid 30 projecting from a side of another side join together in the neighborhood of the vertex of the triangle, and the interface 30 i of the specimen liquid 30 takes a parabolic shape (curved shape) concave toward the side opposite to the movement direction (upstream side) as a whole. Then, surface tension acts on the specimen liquid 30 in the direction indicated by a hollow arrow, and this force makes it easy for the specimen liquid 30 to move in the movement direction.

It is considered that the ease of flow of the specimen liquid 30 when the notched portion 8 is formed depends also on an angle θ at the vertex of the notched portion 8. The angle θ is, for example, not less than 40° and not more than 70°. A suitable range of this angle θ may be set as appropriate in consideration of the viscosity of the specimen liquid 30 and the wettability (the angle of contact with water) of the flow passage 29.

Modified Examples

FIG. 9 shows a modified example of the planar shape of the notched portion 8. It is necessary for the planar shape of the notched portion 8 only to be a shape gradually decreasing in width toward the upstream of the flow passage 29; for example, the shape may be a triangle having sides of different lengths as shown in FIG. 9( a), a trapezoid as shown in FIG. 9( b), a parabolic shape (curved shape) as shown in FIG. 9( c) or a shape in which a central area in the width direction is notched as shown in FIG. 9( d).

Thus, according to the sensor 100, by providing the notched portion 8 gradually decreasing in width toward the upstream of the flow passage 29 on the bottom surface 29 b of the portion of the exit to the concave portion 9 of the flow passage 29, the specimen liquid can be inhibited from stopping in the middle.

FIG. 13, FIG. 14, FIG. 17, FIG. 18 and FIG. 19 show modified examples 1, 2, 3 and 4 of the sensor 100 according to the first embodiment, respectively. These figures are cross-sectional views at the same part as that of FIG. 5.

A sensor 103 of the modified example 1 shown in FIG. 13 is different from the sensor 100 in members constituting the flow passage structure 2. Specifically, in the sensor 103, the first adhesion layer 21 is absent, and the flow passage structure 2 is formed of the first hydrophilic sheet 22, the second adhesion layer 23 and the second hydrophilic sheet 24. In this case, as shown in FIG. 13, the first hydrophilic sheet 22 is disposed on the upper surface 3 b of the detection element 3. The fixing of the flow passage structure 2 is performed, for example, by interposing an adhesive agent between the first hydrophilic sheet 22 and the upper surface 3 b of the detection element 3.

A sensor 104 of the modified example 2 shown in FIG. 14 is the sensor 100 from which the support member 4 is removed. As in the sensor 104, the support member 4 is not always a necessary member and may be absent. When the support member 4 is not provided like this, one side of the flow passage structure 2 floats; however, since the flow passage structure 2 bows like a spring because of this structure, for example, even if a large force acts on the flow passage structure 2 from above when the specimen liquid is made to make contact with the inlet 14, the force is absorbed to suppress the breakage of the flow passage structure 2.

A sensor 105 of the modified example 3 shown in FIG. 17 is the sensor 100 from which the support member 4 is removed, and the bottom surface 29 b of the flow passage 29 of the flow passage structure 2 and the upper surface 3 b of the detection element 3 are substantially flush with each other. Specifically, the flow passage structure 2 has no support member 4, and the first adhesion layer 21, the first hydrophilic sheet 22, the second adhesion layer 23 and the second hydrophilic sheet 24 are formed in order on the substrate 1. Thereby, as shown in FIG. 17, the first hydrophilic sheet 22 which is the bottom surface 29 b of the flow passage 29 of the flow passage structure 2 and the upper surface 3 b of the detection element 3 are substantially flush with each other. Moreover, as shown in FIG. 18, the notched portion 8 is formed by notching a part of the first hydrophilic sheet 22. In this sensor 105, the specimen liquid 30 also projects toward the detection element 3 and the interface 30 i of the specimen liquid 30 is located slightly on the movement direction side of the wall surface 29 b 1 of the notched portion 8. Consequently, the interface 30 i of the specimen liquid 30 easily makes contact with the upper surface 3 b of the detection element 3 substantially flush with the bottom surface 29 b of the flow passage 29, which allows the specimen liquid 30 to flow so as to spread to the upper surface 3 b of the detection element 3. The notched portion 8 may be formed by notching not only the first hydrophilic sheet 22 but also up to the first adhesion layer 21 located there below in the direction of the thickness.

Moreover, in the present modified example, a space is present between the bottom surface 29 b of the flow passage 29 and the detection element 3. In this case, the specimen liquid 30 also easily moves in the movement direction by providing the notched portion 8. Consequently, the specimen liquid 30 is allowed to flow in so as to spread to the upper surface 3 b of the detection element 3 by the interface 30 i of the specimen liquid 30 making contact with the upper surface 3 b of the detection element 3 as described above or by the specimen liquid 30 falling into the space and further moving in the movement direction while making contact with (the side surface of) the detection element 3. The space may be filled by filling the space with a filler or the first hydrophilic sheet 22 may be formed up to a position closer to the detection element 3 compared with the first adhesion layer 21 to thereby make the space narrow.

Moreover, the outlet 18 of the sensor 100 is present as a through hole formed on the upper surface of the flow passage structure 2, that is, the second hydrophilic sheet 24. On the contrary, in a sensor 105(a) of FIG. 17( a), the outlet 18 is located on a side surface of the flow passage structure 2, that is, between the first hydrophilic sheet 22 and the second hydrophilic sheet 24, and in a sensor 105(b) of FIG. 17( b), the outlet 18 is located on a side surface of the flow passage structure 2, that is, between a liquid absorber 25 and the second hydrophilic sheet 24.

A sensor 106 of the modified example 4 shown in FIG. 19 is different from the sensor 105 of the modified example 3 in that the upper surface 3 b of the detection element 3 is present in a position higher than the first hydrophilic sheet 22 which is the bottom surface 29 b of the flow passage 29 of the flow passage structure 2. In this sensor 106, the specimen liquid 30 also projects toward the concave portion 9, and the interface 30 i of the specimen liquid 30 is located slightly on the movement direction side of the wall surface 29 b 1 of the notched portion 8. Consequently, not only operational advantages similar to those of the sensor 105 of the modified example 3 can be obtained but also the interface 30 i of the specimen liquid 30 more easily makes contact with the upper surface 3 b of the detection element 3 present in a position higher than the bottom surface 29 b of the flow passage 29 than in the sensor 105 of the modified example 3, which allows the specimen liquid 30 to flow so as to spread to the upper surface 3 b of the detection element 3. Additionally, the sensor 106 is similar to the sensor 105 of the modified example 3 in that a space is present between the bottom surface 29 b of the flow passage 29 and the detection element 3 and that the position of an outlet 108 is present on a side surface of the flow passage structure 2.

Second Embodiment

FIG. 10 shows a cross-sectional view of a sensor 200 according to a second embodiment. The sensor 200 is different from the sensor 100 according to the first embodiment only in the shape of the wall surface 29 b 1 of the notched portion 8, and the remainder of the structure is the same as that of the sensor 100.

In the sensor 200, the wall surface 29 b 1 of the notched portion 8 is inclined so that the width of the notched portion 8 gradually decreases downward. Therefore, when the notched portion 8 is viewed from above, the wall surface 29 b 1 of the notched portion 8 is seen as shown in FIG. 11.

Inclining the wall surface 29 b 1 of the notched portion 8 as described above makes it easy for the specimen liquid 30 to reach the detection portion 13. That is, an effect of inhibiting the specimen liquid 30 from stopping in the middle can be enhanced. This is because if the wall surface 29 b 1 of the notched portion 8 is inclined so that the width of the notched portion 8 gradually decreases downward, the interface of the specimen liquid 30 more easily takes a shape which is concave toward the upstream as shown in FIG. 10. When the interface of the specimen liquid 30 takes such a shape, surface tension acts in a direction toward the detection element 3 as shown by a hollow arrow, and because of the force, the specimen liquid 30 does not stop at the step portion and more easily moves in the movement direction.

The inclination angle of the wall surface 29 b 1 of the notched portion 8 in the sensor 200 will be described by using FIG. 12. FIG. 12 is an enlarged view of the part of the notched portion 8. When the angle of contact of a certain specimen liquid with the upper surface 29 a of the flow passage 29 is θ₁, the angle of contact with the wall surface 29 b 1 of the notched portion 8 is θ₂ and the inclination angle of the wall surface 29 b 1 is θ₃, in the sensor 200, the inclination angle θ₃ of the wall surface 29 b 1 is set so that the following is satisfied:

θ₁+θ₂−θ₃<90°  (3).

By the expression (3) being satisfied, the interface of the specimen liquid 30 easily takes a shape which is concave toward the upstream as shown in FIG. 10.

Third Embodiment

FIG. 15 shows a cross-sectional view of a sensor 300 according to a third embodiment. As in the second embodiment, the sensor 300 is different from the sensor 100 according to the first embodiment only in the shape of the wall surface 29 b 1 of the notched portion 8, and the remainder of the structure is the same as that of the sensor 100.

In the sensor 200 according to the second embodiment, the wall surface 29 b 1 of the notched portion 8 is inclined so that the width of the notched portion 8 gradually decreases downward, whereas in the sensor 300 according to the third embodiment, the wall surface 29 b 1 of the notched portion 8 is inclined so that the width of the notched portion 8 gradually increases downward.

Inclining the wall surface 29 b 1 of the notched portion 8 as in the sensor 300 makes it easy for the interface of the specimen liquid 30 to be convex toward the detection element 3. At this time, although surface tension acts in a direction toward the upstream, when the part of the specimen liquid 30 bulging toward the detection element 3 makes contact with the upper surface 3 b of the detection element 3, the specimen liquid 30 flows so as to spread to the upper surface 3 b of the detection element 3 as it is.

EXAMPLES Example 1

The ease of flow of a liquid passing through the flow passage 29 depending on a difference in the angle of the notched portion 8 was examined. More specifically, seventeen kinds of sensors having different angles θ of the notched portion 8 shown in FIG. 8 were produced, and a liquid was passed through the flow passage 29 from the inlet 14 and whether the liquid reached the detection element 3 or not was visually checked to thereby examine the ease of flow of the liquid.

The first adhesion layer 21 and the second adhesion layer 23 constituting the flow passage structure 2 were formed of an adhesive tape, and the first hydrophilic sheet 22 and the second hydrophilic sheet 24 were formed of a PET film having undergone a hydrophilic treatment. The first hydrophilic sheet 22 and the second hydrophilic sheet 24 were transparent so that the liquid passing through the flow passage 29 could be visually observed.

The length (the dimension in the x direction) of the flow passage 29 was 40 mm, the width (the dimension in the y direction) was 6 mm, and the height (the dimension in the z direction) was 0.44 mm. The angle of contact of an inner wall of the flow passage 29 of the produced sensor with water was 25°. The shape of the notched portion 8 was an isosceles triangle. As the liquid passed through the flow passage, water was used.

The measurement results are shown in Table 1.

TABLE 1 No. Angle Result 1 28° Bad 2 30° Bad 3 33° Bad 4 42° Good 5 50° Good 6 56° Good 7 60° Good 8 70° Good 9 73° Bad 10 75° Good 11 77° Good 12 81° Good 13 85° Bad 14 86° Good 15 90° Bad 16 116° Bad 17 120° Bad

In Table 1, “Good” indicates that the liquid reached the detection element 3, and “Bad” indicates that the liquid did not reach the detection element 3 (stopped in the neighborhood of the exit of the flow passage).

As shown in the results of Table 1, when the angle θ of the notched portion 8 was in the range of 42° to 86°, the liquid substantially excellently passed and reached the detection element 3. However, even in that range, when the angle θ was 73° and 85°, the liquid did not reach the detection portion 13 and the liquid stopped in the neighborhood of the exit of the flow passage 29. It is considered that this is because the shape of the neighborhood of the exit of the flow passage 29 differed among samples due to manufacture variations among the sensors and the shape difference affected the ease of flow of the liquid. However, even when such manufacture variations are considered, it is considered that, if the angle θ of the notched portion 8 is in the range of 42° to 70°, an effect of facilitating the flow of the liquid is exerted more than the influence of the difference in the shape of the neighborhood of the exit of the flow passage 29.

Therefore, by setting the angle of the notched portion 8 in a predetermined range (the range of 42° to 70° in Example 1), the liquid easily reaches the detection element 3 even if there are manufacture variations.

Example 2

The influence of the flow passage structure 2 disposed on the upper surface of the detection element 3 on the propagation loss of the SAW was examined. Specifically, the detection element 3 in which the first and second IDT electrodes 11 and 12 were covered with a protective layer was prepared, a measurement sample in which the first adhesion layer 21 was disposed on the upper surface of the detection element 3 was produced, and the propagation loss of the SAW was measured. Two kinds of measurement samples (S1, S2) between which the material of the first adhesion layer 21 is different were prepared.

FIG. 16 is a cross-sectional view of the produced measurement sample, and corresponds to the cross section taken along the line A-A′ of FIG. 3. As shown in FIG. 16, the measurement sample is formed of a structure in which the first adhesion layer 21 is disposed immediately above the first and second IDT electrodes 11 and 12.

For both of the two kinds of measurement samples S1 and S2, LiTaO₃ was used as the piezoelectric substrate 10 and SiO₂ was used as the protective layer 26. For the first adhesion layer 21 of the measurement sample S1, a photoresist “TMMR” (trademark) manufactured by Tokyo Ohka Kogyo Co., Ltd was used, and for the first adhesion layer 21 of the measurement sample S2, a silicone resin was used. The thickness of the protective layer 26 was 1.5 μm. The thickness of the first adhesion layer 21 of the measurement sample S1 was 50 μm, and the thickness of the first adhesion layer 21 of the measurement sample S2 was 1.0 mm.

When, as the reference the propagation loss of the SAW of the standard sample in which the first adhesion layer 21 is not disposed, the propagation loss of the SAW of the measurement samples S1 and S2 were measured, the propagation loss was 15 dB in the measurement sample S1, whereas the propagation loss was 3 dB in the measurement sample S2. That is, the propagation loss of the SAW was smaller in the measurement sample S2 than in the measurement sample S1.

It is considered that this difference in propagation loss is due to the difference in the modulus of elasticity of the material forming the first adhesion layer 21. Specifically, while the modulus of elasticity of the photoresist forming the first adhesion layer 21 of the measurement sample S1 is 2 GPa, the modulus of elasticity of the silicone resin forming the first adhesion layer 21 of the measurement sample S2 is 1 MPa, and it is considered that this difference in the modulus of elasticity causes the difference in propagation loss. Since the modulus of elasticity of the material used for the protective layer 26 is 80 GPa, it can be said that the propagation loss of the SAW can be made small by forming the first adhesion layer 21 by using a material having a modulus of elasticity as lower than that of the protective layer 26 as possible. Although there is a difference in the thickness of the first adhesion layer 21 between the measurement sample S1 and the measurement sample S2, since the thickness of the first adhesion layer 21 is larger than the wavelength of the SAW, this thickness difference hardly affects the propagation loss, and it can be said that the difference in propagation loss between the measurement sample S1 and the measurement sample S2 results from the material itself of the first adhesion layer 21.

The invention is not limited to the above-described embodiments and may be carried out in various modes.

The structures of the modified examples 1, 2 3 and 4 in the first embodiment are applicable also to the sensors 200 and 300 according to the second and third embodiments.

While a structure in which the detection portion 13 is formed of a metal film and an aptamer immobilized on the surface of the metal film is described in the above-described embodiments, for example, a structure in which an antibody is immobilized on the surface of a metal film may be adopted. Moreover, when the target substance in the specimen liquid reacts with the metal film, the detection portion 13 may be formed only of a metal film without the use of an aptamer. Further, without the use of a metal film, the area between the first IDT electrode 11 and the second IDT electrode 12 on the surface of the piezoelectric substrate 10 serving as the piezoelectric substrate may be the detection portion 13. In this case, a physical property such as the viscosity of the specimen liquid is detected by attaching the specimen liquid directly to the surface of the piezoelectric substrate 10. More specifically, a change in the phase of the SAW due to a change in the viscosity or the like of the specimen liquid on the detection portion 13 is read.

Moreover, while a structure in which the detection element 3 is formed of a surface acoustic wave element is described in the above-described embodiments, the detection element 3 is not limited thereto; for example, a detection element 3 in which an optical waveguide or the like is formed so that surface plasmon resonance occurs, may be used. In this case, for example, a change in the refractive index of light at the detection portion, or the like is read. Additionally, a detection element 3 in which an oscillator is formed on a piezoelectric substrate such as crystal may be used. In this case, for example, a change in the oscillation frequency of the oscillator is read.

Moreover, as the detection element 3, a plurality of kinds of devices may be provided on the same substrate. For example, an enzyme electrode of an enzyme electrode method may be provided next to the SAW element. In this case, measurement by the enzyme method is possible as well as the immunization method using an antibody or an aptamer, so that items that can be examined at one time can be increased.

Moreover, while the inlet 14 is provided on the upper surface of the flow passage structure 2 in the above-described embodiment, the inlet 14 may be provided on a side surface of the flow passage structure 2.

Moreover, while the flow passage structure 2 is formed by using a plurality of members in the above-described embodiments, it may be formed integrally. Moreover, while the plurality of members constituting the flow passage structure 2 include different kinds of materials, a plurality of members may be formed of one kind of material.

REFERENCE SIGNS LIST

-   -   1: Substrate     -   2: Flow passage structure     -   29: Flow passage     -   29 a: Upper surface (ceiling surface)     -   29 b: Lower surface (bottom surface)     -   29 b 1: Wall surface     -   29 c: Side surface     -   3: Detection element     -   3 b: Upper surface     -   4: Support member     -   5: Thin metal wire     -   6: Terminal     -   7: Pad     -   8: Notched portion     -   9: Concave portion     -   10: Piezoelectric substrate     -   11: First IDT electrode     -   12: Second IDT electrode     -   13: Detection portion     -   14: Inlet     -   15: Space     -   18: Outlet     -   19: First extraction electrode     -   20: Second extraction electrode 

What is claimed is:
 1. A gas turbine engine, comprising: an inner shaft extending axially along the gas turbine engine; a plurality of disks extending radially inwardly and toward the inner shaft; at least one hole in at least one of the plurality of disks; and an obstruction positioned between the inner shaft and an end of the disk having the at least one hole, such that a bore flow that flows along an axial length of the inner shaft is obstructed from flowing along the shaft by the obstruction, and forced to flow radially outward from the obstruction, through the at least one hole, and radially inward toward the inner shaft.
 2. The gas turbine engine of claim 1, further comprising a cone shaft aft of the plurality of disks, and a cavity formed in part by an external portion of the cone shaft, wherein cooled cooling air (CCA) is received aft of a diffuser, caused to flow forward, opposite an aft end of the gas turbine, and into the cavity, and split within the cavity such that some of the CCA is caused to flow forward in the cavity to exit at an aft face of the gas turbine engine.
 3. The gas turbine engine of claim 2, wherein, at the split within the cavity, some of the CCA is caused to flow down the cone shaft toward the aft end of the gas turbine and along an outer surface of a C-T shaft and to a C-T bolted joint of the gas turbine engine.
 4. The gas turbine engine of claim 3, further comprising a hole in another of the plurality of disks, wherein a second cavity is formed in part by the another of the plurality of disks, an inner surface of the C-T shaft, and the inner shaft, such that some of the bore flow obstructed from flowing along the shaft flows through the hole in the another of the plurality of disks, into the second cavity, and rejoins with the bore flow aft of the obstruction.
 5. The gas turbine engine of claim 4, wherein the external portion of the cone shaft is one surface of the cone shaft, and the second cavity is formed in part by a second surface of the cone shaft that is opposite the one surface of the cone shaft.
 6. The gas turbine engine of claim 1, wherein the bore flow that is forced to flow radially outward flows along a first surface of the at least one of the plurality of disks, and flows radially inward along a second surface, opposite the first surface, of the at least one of the plurality of disks.
 7. The gas turbine engine of claim 1, wherein the obstruction is coupled to an outer surface of the inner shaft and the end of the disk having the at least one hole.
 8. A method of assembling a gas turbine engine, comprising: positioning an inner shaft to extend along a rotational axis of the gas turbine engine; positioning disks to extend radially inward toward the inner shaft; forming a hole in a first of the disks; and positioning an obstruction between the inner shaft and an end of the first disk, such that a bore flow that flows along the rotational axis and along the inner shaft is obstructed from flowing along the shaft by the obstruction, and forced to flow radially outward from the obstruction, through the hole, and radially inward toward the inner shaft.
 9. The method of claim 8, further comprising positioning a cone shaft aft of the disks to form a cavity in part by an external portion of the cone shaft, wherein cooled cooling air (CCA) is received aft of a diffuser, caused to flow forward, opposite an aft end of the gas turbine, into the cavity, and split within the cavity such that some of the CCA is caused to flow forward in the cavity to exit at an aft face of the gas turbine engine.
 10. The method of claim 9, wherein, at the split within the cavity, some of the CCA is caused to flow down the cone shaft toward the aft end of the gas turbine and along an outer surface of a C-T shaft and to a C-T bolted joint of the gas turbine engine.
 11. The method of claim 10, further comprising forming another hole in a second of the disks, wherein a second cavity is formed in part by the second of the disks, an inner surface of the C-T shaft, and the inner shaft, such that some of the bore flow obstructed from flowing along the shaft flows through the hole in the second disk, into the second cavity, and rejoins with the bore flow aft of the obstruction.
 12. The method of claim 11, wherein the external portion of the cone shaft is one surface of the cone shaft, and the second cavity is formed in part by a second surface of the cone shaft that is opposite the one surface of the cone shaft.
 13. The method of claim 8, wherein the bore flow that is forced to flow radially outward flows along a first surface of the first disk, and flows radially inward along a second surface, opposite the first surface, of the first disk.
 14. The method of claim 8, further comprising coupling the obstruction to an outer surface of the inner shaft and the end of the first disk.
 15. A method of cooling a gas turbine engine, comprising: directing a bore flow to flow along a rotational axis of an inner shaft of the gas turbine engine and to an obstruction along the inner shaft that obstructs the bore flow from flowing along the shaft, wherein the bore flow is forced radially outward from the obstruction, through a hole in a first disk, and radially inward toward the inner shaft, and wherein the disk extends radially inward toward the inner shaft.
 16. The method of claim 15, further comprising receiving cooled cooling air (CCA) aft of a diffuser, flowing the CCA in a forward direction of the gas turbine engine that is opposite an aft end of the gas turbine, into a cavity, and splitting the CCA within the cavity such that some of the CCA is caused to flow forward in the cavity to exit at an aft face of the gas turbine engine, wherein the cavity is formed in part by an external portion of the cone shaft.
 17. The method of claim 16, wherein, at the split within the cavity, the method further comprises flowing some of the CCA down the cone shaft toward the aft end of the gas turbine and along an outer surface of a C-T shaft and to a C-T bolted joint of the gas turbine engine.
 18. The method of claim 17, further comprising flowing some of the bore flow that is obstructed through a hole in a second disk, into a second cavity that is formed in part by the second of the disks, an inner surface of the C-T shaft, and the inner shaft, and rejoining with the bore flow aft of the obstruction.
 19. The method of claim 18, wherein the external portion of the cone shaft is one surface of the cone shaft, and the second cavity is formed in part by a second surface of the cone shaft that is opposite the one surface of the cone shaft.
 20. The method of claim 15, wherein the bore flow that is forced to flow radially outward flows along a first surface of the first disk, and flows radially inward along a second surface, opposite the first surface, of the first disk. 